【多选题】Lubricating oil in an automobile engine has several tasks to perform:
A.
Reducing friction between moving parts of the engine by lubrication.
B.
Acting as a seal to prevent leakage between parts such as pistons,rings, and cylinders.
C.
Carrying away heat by flowing between friction-generating parts.
D.
Washing away abrasive metal worn from friction surfaces.
【单选题】患者,女,13岁,心脏超声诊断为左侧三房心,以下病理解剖及超声表现描述错误的是()。
E.
副房与左心耳、二尖瓣相连通,通过狭小的口与真性左心房交通
【单选题】以下肥厚型心肌病的超声心动图特征的描述,错误的是()。
【单选题】Diesel engine fuel oil leakage should be drained and additional precautions provided to ____.
A.
return this oil to the proper storage tank
B.
prevent contamination of lubricating oil by fuel oil
C.
ascertain an axxurate measurement of this leakage
D.
drain cooling water system components
【多选题】( 2019 · 南师附中 5 月模拟 ) 理论表明 : 黑洞质量 M 和半径 R 的关系为 = , 其中 c 为光速 , G 为引力常量 . 若观察到黑洞周围有一星体绕它做匀速圆周运动 , 速率为 v , 轨道半径为 r , 则可知 ( )
【单选题】关于肥厚型心肌病的超声心动图征象的描述,不正确的是()。
A.
室间隔厚度>13mm,室间隔厚度与左心室厚度之比>1.3
B.
合并梗阻时有二尖瓣前叶收缩期前向运动(SAM)现象
【单选题】By , prevent leakage between parts such as pistons, rings and cylinders.